Phase sensitive rectifier-amplifier



Dec. 28, 1954 s. HERMAN PHASE SENSITIVE RECTIFIER-AMPLIFIER Filed Nov. 20, 1953 INVENTORZ Jig/var //2PMAA/ BY 9% ,wup/flfim 7 ATTORNEYS.

United States Patent O 2;6,-392 S'ENSITWE RECTlFiER-AMPETFIER Sidney Herman, Brooklyn, N. Y. rippliifatiorr' November '26, 153 53 SeriiiFNii: 393534? 12 claims (Gl'.-307 -'25)' The presentinvention-meta: cs to aphase sensitiveflrec tifier and amplifier, and more particularly to sucli -a'ri amplifier: using semieend otorsl Mostcont'rol equipment',-sucli as servos,"regulatorsyetct use: alternating our" in; indicating devices as t'rfansduc s, usually including It is desirable to c'on vert the alter'r'iatingcurrent to direct c rrent-for eflicieritly using the input energy to drive the 'equipment tcr'be controlled. A preamplifier is often: employedto raise the signal levelg therr a demodulator, or rectifier, is usedtoconvert: the amplified signal to direct current. Furtheramplification may be necessary in accordan e with the power requirements o'f the equiprr'i'er'i't to be con trolled; Gompensat-ing networ s, stabilizingnetworks, and the like areintroduced if necessarysomewhere in the system usually in the directcurrent-sections v Devices for such purpose; now commonly employed-, havethe: drawback of large weight whenusing magnetic amplifiers'aor rather low efficiency whenusing vacuumitubes, due to the requirement for heater current, which is--continuous-, even though the equipment is used only intermittently,- and the resulting heat from the vacuumtubes may raisethe temperature ofthe space in which they are-confiried'toa degreewhichis objectionable and may require cooling equipmentto' be installed. 7

It i's'accordin'gly. an object of the presentinvention to provide a phase sensitive rectifier-amplifier Which 'islight in weight, small, and" yethas high ei'liciency, and withoutany objectionable heating effect.-

It is another object ofthe presentinvent'iomto provide a rectifier-amplifier which is: rugged, resistant .to' mechanical disturbances, and reliable in operation-yet com pact-and of-small size.

In accordance with the present invention; I: employ semiconductors, in a circuit which is so designed as to avoid bulky magnetic or saturabl'e com ion'ents. The exact value's'of the components: may be readily deter mined by engineers skilled in the" art; generalreference may be had to Engineers, Vol: 40; No. 11,. November 1952 entitled Transistor Issue Wh'ere applications, and design considerations are fully discussed, and further exhaustive bibliographiesare given.-

The present inventionessentially consists in providing a' balanced center tappedimpedance in parallel with an input impedance; preferably the center tapped impedmice is a resistance unit, which can be easily adjusted for" perfect balance. The input impedance maybe any conventional small; unsaturated choke, transformer, condenser, or: another resistance; as desired, and dictated by? design considerations-for specific applications; The output'of the center tapped impedance will then provide apain of lines,-. and acenter, or common connection, so that a double ended network is-formed providing two directional signals which are usual in control applicationsr A" pairof r'ectifiers, which preferably are of the silic'onton germanium crystal type; are connected in series' with -thelines=-one for CHCh liIlG-QLHd theo'utput of these rectifiersistaken tothe line terminals, to which the line terminals of a load may be applied; The center, orcommon connection, is" connected to' one side of an -alternating: current power source, of the same frequency as the" input signals The: other side of the power source the'n' forms the common, or center terminal for theouu put of the device according. to the invention;- When there is no input signal the current flowing through the two branches ofthe center tapped impedance will be equal; current flow through the lead components; will be in opposite direction, and the controlled equipment will be held at' a rest position, since theeffects of the currents:

will beieqnah and opposite. Howev'e'niwhen an input Proceedings of the Institute of Radio 2,698,392 Patented Dec.- 28,. 1954 signal is applied the unbalance will be introduced-' iiitd the" double ended network; 1 and} the I currentsthroug'li the of loadindicated, since the load itself forms no part-of the invention, and adaptation of the invention for par: ticular'applications is: conventional.

The invention willbest b'e understood if the following description is read in connection with the accompanying drawings, inwhich,

Figure l is a schcmatie wiring diagram of a rectifieramplifier embodying-the-inve'ntion; and Figure 2 is a schematic diagram showingnic idified form.

Referring now particularly to'Fig'ure 1, 16, 10 are the terminals to which an input signal is to" be' applied: If

desired for the purposes of aparticular application of my invention a preamplifier, 1 1, of known kind may be used, having its output connected to an ordinary outpt'lttransformer 12, forming an input impedance for'the" rec'- tifier-amplifier. Other output-coupling, such as a capacitative coupling may also be used The input signal should be in phase or out of phase with the power source 35 described herein.

The secondary of transformer 12 isconnected to lines 13 and 14. Connected in' parallel with the input irn pedance,-. here transformer 12, is a-balanecd, center tapped impedance, which preferably is formed of fixed resist'- ance units 15 and 16, and an adjustable resistance 17 so that the electrical center of the total resistance of units 15, 16, and 17 may be accurately established Lines 13 and 14' are connected to r'ectifie'rs 19, 20; and the rec-- tifi'ers 19,20 are in turn connected to lines 21, Connected to lines 21, 22 are n-p-n type transistors 23, 24, having their emitter electrodes connected to lines-21-', 22 respectively, and their collector electrodes connected to the output leads 25, 26. Output leads 25, 26 are connected' to loads Z1 and Z2, respectively, which may be relay coils, as previously explained.

The base connections of transistors 23, 24 are connected' over leads 27, 28 to a common terminal 30: A source of power 31, such as a battery 32 is connected between terminal 30 and a common connection 33 of loads Z1, Z2. The polarity of the battery is indicated at Figure 1 and is conventional with the particular type transistor used.

A source of power 35 for phase reference and bias potential which may be an alternating current power line is connected to terminals 36, 37. Theseterrninals are in series with the tap 18 of resistor 17 and common terminal 30, so that a pair of closed circuits will be established as follows: terminal 36, tap 18, thence splitting through impedance' 15-16; thence one branch 13, 19, 21, 23, 27, terminal 30' to terminal 37; and the other branch 14, 20, 22, 24, 28, 30to terminal 37. The currents'in lines 21, 22 will be rectifieddue to the action of rectifiers 19, 20 to provide direct current bias potential for the transistors 23,- 24. These currents will be equal, and since the transistors are connected in 0pposition, as shown, the currents through the loads Zr, and Z2, will be equal and in opposite direction, so that, if these loads represent coils of a differential relay, the relay will be held in an equal position. When however, a control signal is introduced by means of trans former 12, the currents in lines 21, 22 will become unbalanced, thereby changing the previously balanced bias on transsistors 23, 24, rendering one more conductive than the other, and causing unbalanced currents to flow through leads 25, 26 to the loads Z1 and Z2. The power delivered" to these loads can be greatly amplified over the power available at transformer 12, yet the unit may be very compactand eflicient as very little power is wasted by' conversion" into heat as is done in heating the filaments of vacuum tubes when devices using vacuum type tubes are employed.

to be understood that the application" of Figure 2 illustrates a number of modifications which may easily be carried out; like reference numerals refer to like parts of Figure 1. The battery 32 of power source 31 may be replaced by a source of alternating current power 40 in combination with a dry rectifier 42, cuit 41 of conventional design, comprising rectifier 42, and filter network 43. Lines 25, 26, and the common line from terminal 33, here shown as line 44 may be connected to terminals 45, 46, 47, at which point filter networks, compensating network, or ripple smoothing networks may be connected; these networks are conventional and well known in the art. The transistors 23-0, 24-a shown are of the p-n-p type, and therefore the polarity of the rectifiers 19, 20, and of the source of power 41 has been reversed with respect to the polarity of the rectifiers 19, 20 and battery 32, of Figure 1.

In operation, a system using power supply 41 has the advantage that no power source is necessary other than an ordinary line cord to a conventional line socket or plug. When the system is idle, i. e. when it is in balance. the power consumption is very small and may readily be limited to a negligible value by suitable design of the resistances 15 and 16. A further advantage of the system over one using vacuum tubes is that the emitter resistance of the transistors 23, 24, or 23a, 24-a is low, and the collector resistance is high, while the'opposite is true for a similar vacuum tube circuit. Therefore there is little loss of power from the signal power source applied to input 10, or from the reference and bias power source 35 It is therefore seen that I have provided a phase sensitive amplifier and rectifier, which is essentially characterized in that a center tapped impedance 15, 16, 17 is connected in parallel with an input circuit (10, 11, 12) to establish a double ended network; a pair of transistors 23, 24 are symmetrically connected to the outside terminal points of the center tapped impedance so as to provide amplification for power to be delivered to a balanced, center tapped load; and a source of reference voltage, 35, is connected to the center tap 18 of the impedance 15, 16, 17 on the one hand, and to the transistors on the other, so as to provide a balanced reference voltage which will cause equal currents to flow in opposition through the balanced load, but permit large unbalanced currents to flow through the load when an input signal appears across the input circuit, and therefore also across the center tapped impedance.

It will thus be seen that there has been provided by this invention a method and apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

What I claim is:

l. A phase sensitive amplifier-rectifier, comprising a center tapped impedance having a pair of outside terminals and a center terminal, a pair of transistors, having their emitter electrodes each connected to an outside terminal, and having their collector electrodes connected to a load, and a pair of terminals adapted to be connected to a source of power, one, of said pair of terminals being connected to the center terminal of the center tapped impedance, and the other of said pair of termi nals being connected to the bases of both transistors of said pair of transistors.

2. A phase sensitive amplifier-rectifier, comprising a center tapped impedance having a pair of outside terminals and a center tap terminal, a pair of rectifiers, connected to said outside terminals respectively, a pair of transistors, having their emitter electrodes connected to said rectifiers respectively, each rectifier being in series between an outside terminal and a transistor, a balanced, center tapped load, having its center tap connected to the bases of the transistors, and the other load terminals connected to the collector electrodes of the transistors, and a pair of terminals, adapted to be connected to a source of power, one of said terminals being connected to the center tap terminal of said center tapped impedance, and the other of said terminals being connected to the bases of said transistors.

3. A phase sensitive amplifier-rectifier as claimed in claim 2, wherein the source of power is current source.

4. A phase sensitive amplifier-rectifier as claimed in claim 2, including a source of potential connected between the center tap of the load and the cases of the transistors.

5. A phase sensitive amplifier-rectifier as claimed in claim 2, including a rectifier network connected to a source of power, and means connecting the output of said rectifier network in series with the center tap of the load, and the bases of the transistors, to provide a source of direct current potential for the transistor collectorload-base circuit.

6. A phase sensitive rectifier-amplifier, comprising a balanced, center tapped impedance to establish a symmetrical, double ended network, a pair of amplifier means, each connected to one outside terminal of said center tapped impedance, and connection means adapted to be connected to a source of power in series with the an alternating center tap of said impedance and the amplifier means,

so that signals impressed across the center tapped impedance will disturb the balance of the amplifier means and amplification of each amplifier means of the pair will be different from the other.

7. A phase sensitive rectifier-amplifier, comprising a single ended input impedance unit, a balanced, center tapped impedance in parallel with said impedance unit to establish a symmetrical, double ended network, a pair of rectifier means, each connected on one side to the respective terminals of said center tapped impedance unit, amplifier means connected to the other side of said rectifier means, and connection means adapted to be connected to a source of alternating current power in series with the center tap of said impedance, and the amplifier means, so that the rectifier means will rectify power introduced through the connection means, and simultaneous amplification will be eflected under control of signals impressed upon the input impedance unit.

8. A phase sensitive rectifier-amplifier as claimed in claim 7, wherein the balanced, center tapped impedance 6 is a center tapped resistance unit.

9. A phase sensitive rectifier-amplifier as claimed in claim 7, wherein the balanced center tapped impedance comprises a pair of fixed resistances and a tapped, variable resistance connected between said fixed resistances.

10. A phase sensitive rectifier-amplifier as claimed in claim 7, including a split load, having its outside terminals connectedeach to one terminal of said amplifier means,

and its common terminal connected to another terminal of both of said amplifier means.

11. A phase sensitive rectifier-amplifier as claimed in claim 7, including a preamplifier unit connected to said input impedance unit.

12. A phase sensitive rectifier-amplifier, comprising a single ended input impedance unit, a balanced, center tapped resistance in parallel with said impedance unit to establish a symmetrical, double ended network, a pair of dry rectifiers, each connected on one side to the outside terminals of said center tapped resistance, a pair of transistors, each having their collector electrodes connected to the other side of each of said dry rectifiers respectively, a symmetrical split load, having its outside terminals connected to the collector electrodes of said transistors, a common connection point connected to the bases of both of said transistors, a source of potential connected between said common connection point and the common terminal of the split load, and a source of alternating current power connected in series with the center tap of the resistance and the common connection point, so that the currents from the source of alternating current power to the rectifiers, transistors, and the components of the split load will be equal, and, when an additional potential is introduced across the input impedance unit, the currents will become unequal thus effecting a power change to a greater extent than a power change solely due to said additional potential.

Number Name Date Darling Sept. 22, 1953. J 

